"Theme development is a tedious and difficult task, and for the GTK devs to be so careless in breaking their API at every turn disrespects the many hours people put into making themes for it. [...] I was given to believe that this breakage stems from a Microsoft-like climate of preventing users from customizing their systems, and deliberately breaking the work of others so that your 'brand' is the best. Anytime I hear the word 'brand' being used in Linux, I know something valuable is being poisoned." I find the tone of this one a bit too harsh and overly negative at times, but his point still stands.

The official python API is PySide, not PyQt. That is the one actually developed by digia.

Regarding vala, it seems like a really cool idea, but is very immature and has a fair distance to go before it reaches widely useable potential.
I actually wanted to play around with it, until I realised it was basically just for gnome. I've only had bad experiences with gnome, so...

Dolphin does less than konqueror and kommander, but it does have a much more clean and pleasing UI, whilst retaining features like pane splitting, kparts and integrated terminal. Also good is that they have all of the panels and toolbars still fully customizable and removable.
Nautilus has been okay, but pcmanfm/thunar just don't look that good, and the reason we're using file managers instead of just a terminal is for the GUI, right?

It could well be that I have no problems because I'm running a Phenom II 965 quad core, and intending to upgrade to haswell next year, but even on my athlon, the themeing of KDE was something that kept me there, as opposed to the lighter desktops, despite the minor performance regressions. I know you clearly favour performance, but I like my working environment to feel enjoyable, which for me means a consistent and modern appearance.

I can't help you with that directory panel, unless it is folder view, or the classic start menu, which are still bundled with default KDE as plasmoids.